It has appointed the AAR to handle the review as part of a wider strategic programme, which last month saw it undertake a radical rebrand, dropping the name National Asthma Campaign.
Asthma UK wants to raise awareness of the charity's role as experts on the condition and challenge the common perception that it is solely a campaigning organisation.
Direct marketing manager Rachael Williams said: "With the rebrand there is a renewed drive for promotion of our services to people with asthma. This gives us an opportunity to improve our communications with existing and new supporters."
Alison Cowan, assistant director of marketing for individual giving, is overseeing the review. The AAR has shortlisted an undisclosed number of agencies to pitch for the business including incumbent Whitewater. The result is expected to be announced in early August.
The successful agency will work both with the charity's direct marketing and event teams in broadening the scope of Asthma UK's fundraising strategy to develop and grow its supporter base. The aim is to communicate more clearly that Asthma UK is the dedicated UK charity representing the 5.1m people who suffer from the illness.
Last November, Asthma UK created the role of executive director of marketing to lead the repositioning of the charity. It promoted assistant director of marketing Richard Donaldson to the top marketing post.
Last month, Asthma UK launched its biggest campaign of the year. It created an Asthma Attack Card to explain the steps that need to be taken in the event of a sufferer being hit by a severe attack.
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